It’s clear that Reese (Jim Caviezel) and Finch (Michael Emerson) are still figuring out their working relationship on Person of Interest — and that’s part of the fun of watching the two paranoid, highly secretive people tango around situations and cases. And tonight will present their already delicate arrangement with a further challenge, according to executive produer Jonathan Nolan.

“These two characters are still largely negotiating with each other how this is going to work, what the division of labor is going to be, what risks they’ll take, how they’ll tackle certain problems,” he told EW this weekend. “In episode 5, Finch might want to solve a problem one way but Reese has a more direct approach. I just love that slightly Odd Couple-like relationship in which they’re still learning…Although it’s sort of one-sided because Finch knows a lot about Reese and Reese knows very little about Finch. It’s a relationship that’s been a lot of fun for us. We’re carefully mapping out how close these guys get and how fast they get there.”

For Emerson, he hopes it’s a slow walk, as their chemistry — or, as he puts it, “non-chemistry” — comes relatively natural. “It’s not a thing we have to work at much,” he says. “[Caviezel] and I are very different kinds of people. We look differently, and we approach our work differently. I think that plays out well. It’s like we’re from different countries, Jim and I, and that’s good. It’s better if [Finch and Reese] are a bad fit. There’s no drama in it if they suddenly get along easily or if they suddenly find sympathy and ease and good humor and camaraderie. It’s better if all of that just bleeds through very slowly over the course of time.”

And like the relationship that the main characters share, the larger storyline of heavy mythology must also be taken slow, says Nolan. But that has given way to the challenge of being a high-concept procedural. Nolan embraces that, however. “The nice thing about having the case of the week structure is that really that larger story maps out over a length of time in terms of, how much fun are you having investigating a different story each week,” he says. Largely, it seems viewers are liking the ride. The show has averaged a 2.8 rating in the all-important 18-49 demo, and 13.7 million viewers.

Emerson says he enjoys the risk of of the slow-burn story. “On Lost, we touched down on mythology almost every episode. We don’t have that luxury on this show. But maybe it’ll make us to be very disciplined. On Person of Interest, when we get to flashbacks, or backstories of these characters, I think they are going to be handled really efficiently and sparingly.”

With a 13-episode order, Nolan is hopeful he’ll have the chance to tell the story he has in mind (and yes, he does have a plan for the very end of the show). “It’s a fun problem to have that you wake up every day hoping to tell a story that people find compelling and engaging, and if you do, you get to keep telling that story, which seems fair.”